A songwriter is a musician who professionally composes musical compositions or writes lyrics for songs, or both. The writer of the music for a song can be called a composer, although this term tends to be used mainly in the classical music genre and film scoring. A songwriter who mainly writes the lyrics for a song is referred to as a lyricist. The pressure from the music industry to produce popular hits means that song writing is often an activity for which the tasks are distributed among a number of people. For example, a songwriter who excels at writing lyrics might be paired with a songwriter with the task of creating original melodies. Pop songs may be composed by group members from the band or by staff writers – songwriters directly employed by music publishers. Some songwriters serve as their own music publishers, while others have external publishers.

A composer is a person who writes music. The term is especially used to indicate composers of Western classical music, or those who are composers by occupation. Many composers are, or were, also skilled performers of music.